Add an installd command to prune dex files.

This is a straightforward port of logic from
PackageManagerService#pruneDexFiles.

bug: 14407732

Change-Id: I892cff027ddcbb1a4fb37a7af5ecf1697049a188
diff --git a/cmds/installd/installd.h b/cmds/installd/installd.h
index 0f7119d..50ba39a 100644
--- a/cmds/installd/installd.h
+++ b/cmds/installd/installd.h
@@ -157,7 +157,7 @@
 
 int delete_dir_contents(const char *pathname,
                         int also_delete_dir,
-                        const char *ignore);
+                        int (*exclusion_predicate)(const char *name, const int is_dir));
 
 int delete_dir_contents_fd(int dfd, const char *name);
 
@@ -216,3 +216,4 @@
 int linklib(const char* target, const char* source, int userId);
 int idmap(const char *target_path, const char *overlay_path, uid_t uid);
 int restorecon_data();
+int prune_dex_cache();